# Building a water jet cutter using Arduino, CNC shield and GRBL firmware

I am building a water jet cutter using Arduino Uno and CNC shield for control. The CNC shield uses A4988 drivers to control the stepper motors. I uploaded the GRBL (for this shield) firmware to the Arduino and got ready to use Universal G-code Sender to send g-code instructions that the machine will work on. Now my question is this: if I want to choose to work on full step, half step or 1/16th step mode, does the Arduino, shield or the GRBL firmware know what my option is? I am asking this in order to know if I can use another motor driver (if I choose full step and the GRBL handle it well then I can use L297 driver for example, which only work on full and half step mode). I hope I made it clear...

• Rather than use bold you should hyperlink to the datasheets or project home pages. Most people aren't going to know what GRBL is, for example. – Transistor Jan 12 at 19:01

Any stepper controller won't know or care if the driver is using full step or some fractional micro-step. All it needs to know is the number of steps per unit distance. For Grbl this is configured in the $parameters. Table 1. Default stepper configuration for GRBL 1.1. $100=250.000    X steps/mm
$101=250.000 Y steps/mm$102=250.000    Z steps/mm


Reference: Grbl 1.1 Configuration.

Grbl is a free, open source, high performance software for controlling the motion of machines that move, that make things, or that make things move, and will run on a straight Arduino. If the maker movement was an industry, Grbl would be the industry standard. Source: Grbl home.

• I know but when UGS generates the G-code for 1/16th step mode while I am actually using full step mode, it will give me the wrong number of steps, right?? – Yuri Jan 12 at 19:15
• I'm not familiar with UGS and can't find the configuration settings on the website but I presume it's just a matter of configuring UGS and Grbl the same way. Can you point me to the UGS configuration page? – Transistor Jan 12 at 19:39
• github.com/gnea/grbl/wiki/Grbl-v1.1-Configuration – Yuri Jan 12 at 20:31
• youtube.com/watch?v=-ssuoF2oXGg – Yuri Jan 12 at 20:32